The Poleaxed sourcebook lists some 50 Lancastrians in total including these key magnates present at the battle: Somerset, Exeter, Devon, Trollope, Codnor, Fitzhugh, Geystoke, Clifford, Roos, and Northumberland.
The same source suggests that Clifford, Roos, Northumberland and (another?) Percy were in the same 'battle' although it lists Clifford as the 'battle commander'. Given their affiliation and connections this is a very reasonable suggestion that they fought together.
Hope that helps.